Semianalytical Solution for Dual-Probe Heat-Pulse Applications that Accounts for Probe Radius and Heat Capacity
Semianalytical Solution for Dual-Probe Heat-Pulse Applications that Accounts for Probe Radius and Heat Capacity
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DOI：
10.2136/vzj2011.0112
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发表时间：
2012-05-01
影响因子：
2.8
通讯作者：
Hopmans, Jan W.
中科院分区：
文献类型：
--
作者：
Knight, John H.;Kluitenberg, Gerard J.;Hopmans, Jan W.
双探头热脉冲法是测量土壤热物性的有效方法。测量是用一个传感器进行的，该传感器具有两个平行的圆柱形探头：一个用于将热脉冲引入土壤（加热器探头），另一个用于测量温度变化（温度探头）。我们提出了一个半解析解，占有限半径和有限的加热器和温度探头的热容量。通过将探针视为圆柱形理想导体，得到了该解的拉普拉斯变换的封闭形式表达式。对拉普拉斯域解进行数值反演。对于两个探头具有相同的半径和热容量的情况下，我们表明，它们的有限性质具有相同的影响，由温度探头接收的热脉冲信号。探针的有限半径导致热脉冲信号在时间上更早到达。随着探头半径的增加，这种时间偏移的幅度也会增加。探头有限热容的影响取决于探头热容（C-0）与土壤热容（C）的比值。与C-0/C = 1的情况相比，热脉冲信号的幅度减小（即，温度变化较小），最大温升出现在C-0/C > 1时。当C-0/C < 1时，信号幅度增大，最大温升出现的时间提前。半解析解适用于探针半径（a（0））与探针间距（L）之比满足a（0）/L条件的DPHP应用
The dual-probe heat-pulse (DPHP) method is useful for measuring soil thermal properties. Measurements are made with a sensor that has two parallel cylindrical probes: one for introducing a pulse of heat into the soil (heater probe) and one for measuring change in temperature (temperature probe). We present a semianalytical solution that accounts for the finite radius and finite heat capacity of the heater and temperature probes. A closed-form expression for the Laplace transform of the solution is obtained by considering the probes to be cylindrical perfect conductors. The Laplace-domain solution is inverted numerically. For the case where both probes have the same radius and heat capacity, we show that their finite properties have equal influence on the heat-pulse signal received by the temperature probe. The finite radius of the probes causes the heat-pulse signal to arrive earlier in time. This time shift increases in magnitude as the probe radius increases. The effect of the finite heat capacity of the probes depends on the ratio of the heat capacity of the probes (C-0) and the heat capacity of the soil (C). Compared with the case where C-0/C = 1, the magnitude of the heat-pulse signal decreases (i.e., smaller change in temperature) and the maximum temperature rise occurs later when C-0/C > 1. When C-0/C < 1, the magnitude of the signal increases and the maximum temperature rise occurs earlier. The semianalytical solution is appropriate for use in DPHP applications where the ratio of probe radius (a(0)) and probe spacing (L) satisfies the condition that a(0)/L